Editor's note: Paul Begala, a Democratic strategist and CNN political contributor, was a political consultant for Bill Clinton's presidential campaign in 1992 and was counselor to Clinton in the White House. Begala is not a paid political consultant for any politicians or candidates. His new book is "Third Term: Why George W. Bush Loves John McCain."

Paul Begala says he's played a behind-the-scenes role in most of the presidential debates of the past 20 years.

(CNN) -- I have been involved in most of the presidential and vice presidential debates over the past 20 years.

I've done debate prep, been a spin doctor, convened the greatest comedy writers in Hollywood in a one-liner factory, even played George W. Bush for Al Gore's practice debates.

So now that I'm merely observing the debates as a CNN political analyst, I thought I'd offer our readers and the candidates my Top 10 rules for debates:

1.Debates are easy. It's a dirty little secret, but for all the hype, debates are easier than news conferences, town-hall meetings or in-depth, one-on-one interviews on Sunday morning television. You hit your mark, you deliver your lines, you try not to pass out or throw up, then you declare victory. So relax, candidates, you might even have fun.

2.20 questions, 20 answers, one message. This is not "Jeopardy," where you're at the mercy of the topics Alex Trebek (or in this case, Jim Lehrer, Gwen Ifill, Tom Brokaw and Charlie Gibson) select. There is really only one question in an election: Why should we vote for you and not the other candidate?

John McCain's basic message, it seems to me, is, "I'm experienced, Obama's too risky." Barack Obama's, on other hand, is, "I'm for change, McCain is more of the same."

Each answer to each question should be a variation on that theme. A good debater introduces or ends lots of answers with "That's another example of why we need change... (or experience, or whatever it is he or she is running on) ..."

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3. Familiarity matters. The best debate preps are like SAT courses; they focus on test familiarity more than substantive details. Familiarity brings comfort. Comfort breeds confidence. Confidence delivers victory. In 1992, we Clintonites were so eager to make our man comfortable in the town-hall debate in Richmond, Virginia, that we brought the stools we'd used for debate prep to the debate site.

Then someone -- and I'm not ratting anyone out here -- replaced the "official" stools at the debate site with the ones we'd been practicing with. We wanted Gov. Bill Clinton to be completely at ease in his surroundings, right down to his butt.

4.Don't cram. If your debate prep is dominated by propeller-heads, you're in trouble. I love the nerds, Lord knows, but they can overwhelm you. In 1984, the brilliant Richard Darman overloaded Ronald Reagan with minutiae, perhaps in an effort to dispel rumors that the Gipper had lost a step.

The strategy blew up in the Reagan campaign's face. In his first debate with Walter Mondale, Reagan stumbled and stammered. There was too much new information clanging around in his brain. But by the second debate, he blew away concerns about his age. He did this not with a rapid-fire recitation of statistics, but with a classic Reagan quip: "I will not use my opponent's youth and inexperience as an issue in this campaign." Which leads me to my next rule:

5.Wit is sticky.John Kerry bested George W. Bush in all of their debates, according to the polls. And yet voters were left without any take-home point. That's because Kerry not only lacked a clear, coherent message (see No. 1 above), he didn't use humor. In fact, I was told that one of his aides later bragged that Kerry had refused to use any of the "cute lines" my Hollywood writers had sent his way -- as if being witty were beneath him.

The most memorable lines are often the funniest. Think of jug-eared Ross Perot crowing, "If you have a better plan ... I'm all ears." Or former POW McCain saying of a plan to build a museum at the site of the Woodstock concert, "I'm sure it was a cultural and pharmacological event. But I could not attend. I was tied up at the time."

Chris Rock recently told Larry King that people only laugh at a line if they see some truth in it. Smart candidates ought to heed Rock's observation.

6.The camera is always on. So, by the way, is the microphone. Al Gore had been promised that there would be no reaction shots in his first debate with George W. Bush. That, of course, was wrong. So, while Gore trounced Bush on the issues, the post-debate cut-and-paste jobs caught Gore sighing repeatedly and rolling his eyes endlessly.

Gore was in fact frustrated, perhaps understandably so. But never let 'em see you sweat -- or sigh. No matter what they tell you, the camera (and the microphone) is always on.

One of the most important skills for a debater is knowing what to do when the other candidate is attacking you. Poor Dan Quayle had his famous deer-in-the-headlights moment when Lloyd Bentsen skewered him ("Senator, you're no Jack Kennedy.") But Obama was better coached.

Every time McCain launched a broadside, Obama would shake his head slowly, paint a half-smile on his face, look down and jot a note. It doesn't matter what he was writing. It could have been gift ideas for his daughter's birthday. But he did not glare angrily or stare blankly.

7.Create a moment. The voters who will decide the election are unlikely to be watching the debate in its entirety. Instead, they will see brief clips repeated frequently.

The job of a debater is to force his or her way into one of those clips by creating a moment. The easiest way to do this is by a direct address: "John, you said we would be greeted as liberators. You said we knew where the weapons of mass destruction were. You were wrong."

They say actors have a hard time knowing what to do with their hands. For debaters, the challenge is what to do with their eyes. The best debaters -- Reagan, Clinton -- spent much of their time creating moments by either fixing their eyes on their opponent when launching a barb or looking directly into the camera.

In the first debate, McCain rarely if ever engaged either Obama or the audience with his eyes, preferring instead to direct all his remarks to moderator Jim Lehrer. You can bet his team will correct that mistake by the second debate.

8.Don't be a lawyer. I am burdened with a legal education, as are Sens. Barack Obama and Joe Biden. Civilians think lawyers are good debaters. Wrong. They're often effective advocates, but the structure of a legal argument is often this: facts, reasoning, supporting evidence, conclusion. A political debater must start with the conclusion, then follow up with reasoning and facts and analysis.

Compare McCain's strong performance at Pastor Rick Warren's Saddleback Civil Form with Obama's thoughtful, but meandering, answers. It was McCain's best moment of the campaign thus far.

But by the time the first debate rolled around, Obama had in part stifled his inner law professor. Still, his habit of conceding a small point to make a larger one, ("Senator McCain is right when he says we need earmark reform, but ...") while effective in a classroom or a courtroom, was taken out of context and caricatured as weakness. Look for Obama to start more sentences with "Senator McCain is wrong, and here's why ... " or "Senator McCain just doesn't get it, because ... "

9.Small people make small points. Both Obama and McCain got lost in the weeds in the first debate over whether Henry Kissinger supports presidential negotiations with Iran. With all due respect to Dr. Kissinger, who the heck cares?

McCain should have gone to his larger message: "This is just another example of how dangerous and risky Senator Obama's lack of experience is." And Obama should have gone to his: "The failed, old status quo of Bush and McCain has only strengthened Iran. I want a tougher, smarter, new approach."

When Bob Dole was hammering Bill Clinton on what Clinton thought were cheap attacks in their 1996 debate in San Diego, California, Clinton went big, winning the debate not by responding, but by going to his larger message. "I could respond in kind," he lectured Dole, "but a political attack never created a single job, a negative ad never educated a child, a cheap shot never comforted a senior citizen or cleaned up a toxic waste site ..." Clinton went big and he won big.

10.Debates are more often lost than won. When Gerald Ford told Jimmy Carter that Eastern Europe was not under Soviet domination in 1976, it might have cost him the election.

Candidates can be certain that any mistake will be played -- and overplayed -- in the media. How do you avoid gaffes? Well, by observing points 1 through 9 above. But even more than that, I believe self-confidence is the best defense mechanism.

I coach Little League. The best way to ensure that a kid strikes out is to tell him as he walks up to the plate, "Don't strike out, Charlie. Whatever you do, don't strike out."

Politicians are a lot like Little Leaguers (although I don't think I'd trust them with aluminum bats). They crave confidence. And the more confident they are, the better they're likely to do.

Before every debate, the last thing I'd whisper in Bill Clinton's ear before he walked on stage was, "Trust your instincts. They're the best I've ever seen. If something pops into your head, say it." Of course, it helps if your candidate truly is the best you've ever seen -- as Clinton was.

The opinions expressed in this commentary are solely those of the writer.